The present invention relates to an air pump apparatus for sucking and/or discharging air. Particularly, the present invention pertains to an air pump apparatus that is suitable for use in a vacuum suction type pick-up tool used in a clean room to pick up a semiconductor wafer or the like.
Air pump apparatuses are conventionally used in picking up an object such as a semiconductor wafer by using vacuum suction or in scattering materials by using discharge function of the air pump apparatus. Such air pump apparatuses can be also used in aeration of water in an aquarium for keeping goldfish or other aquatic animals or plants. Thus, air pump apparatuses are used in a variety of fields.
Such an air pump apparatus is disclosed for example in U.S. Pat. No. 4,170,439, Japanese Utility Model Application Laid-Open (Kokai) No. 63-46704 or Japanese Utility Model Registration No. 2565626. The air pump apparatus disclosed in No. 2565626 comprises a plurality of diaphragms disposed in a pump chamber and the diaphragms are driven by an electromagnetic drive means utilizing an electromagnet and permanent magnet to conduct air inlet (suction) and air outlet (discharge) operations.
The diaphragm-type air pump apparatuses including those disclosed in the above publications have several advantages over the air pump apparatuses of other types: for example, the diaphragm-type air pump apparatuses can operate without oil and thus can avoid contaminating the surroundings; they tend to produce low noise and oscillation; and the constituent parts thereof have an extended lifetime, reducing the burdens in maintaining the diaphragm-type air pump apparatuses. Therefore, the diaphragm-type air pump apparatuses are suitable for such a use that requires functional steadiness of the pump for an extended period of time and in that contamination of the surroundings should be avoided, e.g., for use as a discharge pump for aeration of water in an aquarium or for use as a suction pump to pick-up a semiconductor wafer using vacuum suction.
In the prior art, however, when it became necessary to increase the pump capacity (or performance) beyond an adjustable range of a single pump apparatus (for example when the aquarium was replaced by a significantly larger one or when it became necessary to pick up a wafer having a significantly larger size and weight), either the entire pump apparatus had to be replaced by a new pump apparatus having a sufficiently high pump capacity or one or more additional pump apparatuses having a similar pump capacity had to be connected to the existing pump apparatus in series by using external piping.
In the former case, the user need to purchase an expensive high-capacity pump apparatus and has to find a new usage for the replaced pump apparatus or wastefully discard it while in the latter case, the external piping and additional power supply and control devices are necessary besides the additional pump main bodies, and they would not only make the total apparatus size considerably larger but also render the operation of the apparatus complicated. Also, the connection of the separate pump apparatuses using the external piping would be quite cumbersome and not readily achieved. Thus, in both cases, the user has to bear undesirable expenses and other burdens. On the part of pump apparatus manufacturers also, there was a problem that they had to provide various types of air pump apparatuses having different pump capacities, and this hindered simplification of the product management and cost reduction of the products.
In view of such problems of the prior art and the recognition by the inventors, a primary object of the present invention is to provide an air pump apparatus that allows easy change of the number of pump mechanisms contained therein and easy connection between the pump mechanisms.
A second object of the present invention is to provide an air pump apparatus that allows addition of a pump mechanisms without considerable increase in the pump apparatus size.
A third object of the present invention is to provide an air pump apparatus that allows an easy electrical connection from the power source to the pump mechanisms contained in the pump apparatus as well as easy operation of the pump mechanisms.
A fourth object of the present invention is to provide a diaphragm-type pump mechanism adapted so as to be easily added to or removed from an air pump apparatus.
According to the present invention, these and other objects can be accomplished by providing an air pump apparatus, comprising: a first pump mechanism; and a pump case assembly forming a first air-tight pump chamber in that the first pump mechanism is contained, wherein the first pump mechanism comprises: a base frame having a first end and a second end opposite to the first end, the first and second ends of the base frame defining an axial direction of the air pump apparatus; mutually opposing first and second diaphragms defining first and second diaphragm chambers on lateral sides of the base frame respectively; electromagnetic drive means for driving the first and second diaphragms so as to expand and contract the first and second diaphragm chambers; a first inlet port defined in the first end of the base frame for communicating air into the first diaphragm chamber upon expansion of the first diaphragm chamber, with a first one-way valve being provided between the first inlet port and the first diaphragm chamber for permitting air flow only into the first diaphragm chamber; a second inlet port defined in the base frame for communicating air into the second diaphragm chamber upon expansion of the second diaphragm chamber, a second one-way valve being provided between the second inlet port and the second diaphragm chamber for permitting air flow only into the second diaphragm chamber; a first outlet port defined in the base frame for discharging air from the first diaphragm chamber upon contraction of the first diaphragm chamber, a third one-way valve being provided between the first outlet port and the first diaphragm chamber for permitting air flow only out of the first diaphragm chamber; and a second outlet port defined in the second end of the base frame for discharging air from the second diaphragm chamber upon contraction of the second diaphragm chamber, a fourth one-way valve being provided between the second outlet port and the second diaphragm chamber for permitting air flow only out of the second diaphragm chamber, and the second outlet port being in axial alignment with the first inlet port, and wherein the first inlet port and the second outlet port of the first pump mechanism are in flow communication with outside of the first pump chamber, and the first outlet port and the second inlet port of the first pump mechanism are in flow communication with the first pump chamber.
In the air pump apparatus constructed as above, since the pump mechanism is implemented as an independent unit, addition of a pump mechanism can be readily carried out. The pump case assembly defining the air-tight pump chamber for containing the pump mechanism therein to make a pump unit comprising two series-connected diaphragm chambers can be easily modified in accordance with addition or removal of a pump mechanism. Since the diaphragm chambers are defined on lateral sides of the base frame of the pump mechanism, the pump mechanism has a relatively small axial size and thus achieving an air pump apparatus having a reduced axial length. This feature will be particularly preferable when achieving a multi-unit air pump apparatus comprising a plurality of series connected pump mechanisms. Further, since the first inlet port and the second outlet port of the first pump mechanism is in axial alignment, an additional pump mechanism having an identical configuration to the first pump mechanism can be quite easily aligned with and connected to the first pump mechanism without using an external pipe or the like, to thereby simplify the connection and achieve a compact air pump apparatus. Thus, the pump capacity of the pump apparatus can be varied in a wide range by changing the number of pump mechanisms contained in the air pump apparatus without replacing the entire air pump apparatus with another. This feature may be beneficial for both users and air pump manufactures in view of the cost.
Preferably, the pump case assembly comprises: a first case member including a base plate extending generally perpendicularly to the axial direction, the base plate having: a first surface on which the first pump mechanism is attached; a second surface opposite to the first surface; and a through-hole extending through the base plate at a position axially aligned with the first inlet port and the second outlet port of the first pump mechanism; and a second case member attached to the first case member so as to form the first air-tight pump chamber, the second case member being provided with a through-hole at a position axially aligned with the first inlet port and the second outlet port of the first pump mechanism, wherein the first inlet port of the first pump mechanism is in flow communication with outside of the first pump chamber via one of the through-holes provided to the base plate of the first case member and the second case member, and the second outlet port of the first pump mechanism is in flow communication with outside of the first pump chamber via the other of the through-holes provided to the base plate of the first case member and the second case member.
According to a preferred embodiment of the present invention, the first inlet port of the first pump mechanism is connected to the through-hole provided to the second case member, and the second outlet port of the first pump mechanism is connected to the through-hole provided to the base plate of the first case member.
Further preferably, the second surface of the base plate of the first case member is adapted so as to be capable of attaching thereto another pump mechanism having an identical configuration to the first pump mechanism with a first inlet port of the another pump mechanism being connected to the through-hole of the base plate of the first case member so that when the another pump mechanism is attached to the second surface of the base plate of the first case member, the second outlet port of the first pump mechanism and the first inlet port of the another pump mechanism are in flow communication via the through-hole of the base plate of the first case member. In this way, a second pump mechanism having an identical configuration to the first pump mechanism can be easily attached directly without using external piping or the like to the second surface of the base plate of the first case member with a first inlet port of the second pump mechanism being connected to the through-hole of the base plate of the first case member so that the first and second pump mechanisms are connected in series via the through-hole of the base plate.
If the pump case assembly further comprises a third case member attached to the first case member so as to form a second air-tight pump chamber for containing the second pump mechanism therein, the third case member being provided with a through-hole at a position axially aligned with a second outlet port of the second pump mechanism so that the through-hole is connected to the second outlet port of the second pump mechanism, and a first outlet port and a second inlet port of the second pump mechanism being in flow communication with the second pump chamber, a compact two-unit pump apparatus can be achieved easily and at low cost.
Similarly, a compact three-unit pump apparatus will be achieved easily and at low cost if the pump apparatus further comprises a third pump mechanism having an identical configuration to the first pump mechanism, and the pump case assembly further comprises: a third case member having an identical configuration to the first case member and axially aligned with the same so that a first surface of a base plate of the third case member faces the second surface of the base plate of the first case member, the third pump mechanism being attached to the first surface of the base plate of the third case member with a second outlet port of the third pump mechanism being connected to a through-hole of the base plate of the third case member; and a fourth case member interposed between the first and third case members, the fourth case member being attached to the first case member so as to form a second air-tight pump chamber for containing the second pump mechanism therein and attached to the third case member so as to form a third air-tight pump chamber for containing the third pump mechanism therein, wherein the fourth case member is provided with a through-hole at a position axially aligned with-a second outlet port of the second pump mechanism and a first inlet port of the third pump mechanism so that the through-hole is connected to both the second outlet port of the second pump mechanism and the first inlet port of the third pump mechanism and wherein a first outlet port and a second inlet port of the second pump mechanism are in flow communication with the second pump chamber while a first outlet port and a second inlet port of the third pump mechanism are in flow communication with the third pump chamber.
A four-unit pump apparatus can be achieve if the three-unit pump apparatus further comprises a fourth pump mechanism having an identical configuration to the first pump mechanism and attached to a second surface of the base plate of the third case member with a first inlet port of the fourth pump mechanism being connected to the through-hole of the base plate of the third case member, and the pump case assembly further comprises a fifth case member attached to the second surface of the base plate of the third case member so as to form a fourth air-tight pump chamber for containing the fourth pump mechanism therein, wherein the fifth case member is provided with a through-hole at a position axially aligned with a second outlet port of the fourth pump mechanism so that the through-hole is connected to the second outlet port of the fourth pump mechanism and wherein a first outlet port and a second inlet port of the fourth pump mechanism are in flow communication with the fourth pump chamber.
Thus, multi-unit pump apparatuses comprising different pump mechanisms connected in series can be achieved easily and at low cost by using common component parts and without external piping. In other words, the pump capacity of the pump apparatus can be varied in a wide range by changing the number of pump mechanisms contained in the air pump apparatus without replacing the entire air pump apparatus with another.
Preferably, the air pump apparatus comprises a lid member disposed at an axial end of the air pump apparatus, the lid member comprising: an air chamber holding a filter therein; and an air passage having one end connected to the air chamber and the other end connected to outside of the air pump apparatus. If the air chamber of the lid member is axially aligned with the first inlet port and the second outlet port of the first pump mechanism, the air chamber can be easily connected without using additional pipe or the like to the first inlet port or the second outlet port of an adjacent pump mechanism. Thus, by disposing the lid member such that air is taken into the air pump apparatus via the air passage and the filter of the lid member, small particles or the like can be prevented from entering the air pump apparatus. If the lid member is disposed such that air is discharged from the air pump apparatus via the filter and the air passage of the lid member, it is possible to prevent the air pump apparatus from discharging small particles or the like. Such an air pump apparatus is suitable for use in a clean room or the like where contamination of the surroundings should be avoided. In view of facilitating connection of an external device such as a tube, nozzle or the like to the air passage in the lid member, it may be preferable if the air passage of the lid member extends generally perpendicularly to the axial direction so that the other end of the air passage is located (or opened) on a side of the air pump apparatus.
Further, in view of facilitating the electrical connection for the pump mechanism(s) in the air pump apparatus, it will be beneficial if an axially extending joint member for securing the pump mechanisms in the air pump apparatus is made of electrically conductive material so that electric power is supplied to the electromagnetic drive means of each pump mechanism via the joint member. In this way, separate parts for establishing an electric path to the electromagnetic drive means becomes unnecessary, simplifying the configuration of the air pump apparatus and facilitating the assembly of the same. Particularly in a multi-unit pump apparatus comprising more than one pump mechanisms, electric power can be supplied from a common power source to the electromagnetic drive means of each pump mechanism via the joint member so that the pump mechanisms can be controlled simultaneously by a common operation switch.
In view of achieving an air pump apparatus having a reduced axial length, the electromagnetic drive means of the first pump mechanism preferably comprises an electromagnet disposed longitudinally alongside the base frame and a pair of arms which are vibrated substantially symmetrically in accordance with alternation of a magnetic field generated by the electromagnet and connected to the first and second diaphragms respectively. The symmetrical vibration of the pair of arms is also preferable in view of low noise generation.
In a preferred embodiment of the present invention, the second inlet port of the first pump mechanism is defined in the first end of the base frame and the first outlet port of the first pump mechanism is defined in the second end of the base frame so that the first and second inlet ports are defined in the same end of the base frame of the pump mechanism while the first and second outlet ports are defined in the same end of the base frame. Such a port arrangement may be also preferable in view of the reduced axial size of the air pump apparatus.
In view of facilitating the attachment of the pump mechanism(s) to the pump case member, it will be preferable if the through-hole of the base plate of the case member is defined by a tubular port having a first edge axially projecting from the first surface of the base plate of the first case member and a second edge axially projecting from the second surface of the base plate of the first case member, the first edge of the tubular port being adapted to be fittingly engageable with the second outlet port of the first pump mechanism and the second edge of the tubular port being adapted to be fittingly engageable with the first inlet port of the another pump mechanism. In this way, the connection of the inlet or outlet port of the pump mechanism to the through-hole of the pump case member can be facilitated and ensured.
According to another aspect of the present invention, there is provided a diaphragm-type pump mechanism, comprising: a base frame having a first end and a second end opposite to the first end, the first and second ends defining an axial direction of the pump mechanism; a diaphragm defining a diaphragm chamber in the base frame; an electromagnetic drive means for driving the diaphragm so as to expand and contract the diaphragm chamber, an inlet port defined in the first end of the base frame for communicating air into the diaphragm chamber upon expansion of the diaphragm chamber, with a first one-way valve being provided between the inlet port and the diaphragm chamber for permitting air flow only into the diaphragm chamber; an outlet port defined in the second end of the base frame for discharging air from the diaphragm chamber upon contraction of the diaphragm chamber, a second one-way valve being provided between the outlet port and the diaphragm chamber for permitting air flow only out of the diaphragm chamber, wherein the inlet port and the outlet port are in axial alignment with each other, and the electromagnetic drive means is disposed alongside the base frame.
Such a pump mechanism can be contained in an air-tightly sealed pump chamber to make a pump unit comprising series-connected two diaphragm chambers. Since the electromagnetic drive means is disposed alongside the base frame, the pump mechanism has a relatively small axial length and thus is suitable for achieving a multi-unit pump apparatus comprising more than one series-connected such pump mechanisms.
Preferably, the diaphragm defines the diaphragm chamber on a lateral side of the base frame and wherein the electromagnetic drive means comprises an electromagnet disposed longitudinally alongside the base frame and an arm vibrated in accordance with alternation of a magnetic field generated by the electromagnet and connected to the diaphragm.